View Full Version : Initial brake bleeding: can I "over-plunge" the MC?
Grubester
04-04-2025, 09:15 AM
Today I will start brake bleeding in my Mk 4 roadster, non-power brakes.
The "complete kit" pedal assembly was installed per manual, but is there an initial adjustment of the brake pedal to prevent forcing the piston in the MC into an "over-plunged" condition?
It would seem that a pedal stop is preferred to jamming the MC piston into a cramped/stopped position.
michael everson
04-04-2025, 11:30 AM
You will be fine
Mike
J R Jones
04-04-2025, 11:38 AM
My suggestion here may be over-cautious, but it has worked for me. I am not concerned about over-stroking in the early stages of bleeding but when a firm pedal is achieved, I take a couple of short strokes at each caliper so that there is pressure/flow through the bleeder as it is closed. My concern is for having the bleeder open when the stroke stops and air could back-flow.
jim
Mike.Bray
04-04-2025, 01:31 PM
On these cars if you gravity bleed for a few hours you will be 95% there. Use these to catch the fluid. https://www.amazon.com/dp/B000CMDP44?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
gbranham
04-04-2025, 07:38 PM
Or pressure bleed in 15 minutes, and done.
212160
Grubester
04-04-2025, 09:57 PM
Thanks for all the suggestions! I did call Dan Golub to briefly ask a couple questions also. But I successfully bench bled the two master cylinders for the brakes and then did the normal bleeding starting from the remote calipers. It's unusual in my experience to have two separate systems but you more or less work with them in parallel. Went over it a couple of times to make sure the final air was out. Only two small leaks that responded to a little bit of additional tightening. It's a nice Milestone to be completing.
Highplainsdakota
04-09-2025, 01:41 PM
The wilwood instructions say to bench bleed the MCs level before installation. I decided to just tilt the chassis. Just a thought if your at this step!
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Avalanche325
04-09-2025, 02:27 PM
You should always bench bleed MCs.
Don't even think of a pedal stop on brakes. One day you might need that last tiny bit.
when I switched to Tilton MC's I also had this question so I called them to ask. According to their tech, overplunging was not a cause for concern, they would be fine.
Wizbangdoodle
04-09-2025, 05:45 PM
When it came time to bleed my brakes, I read a lot of threads on it, and I mean a LOT. I finally came to the conclusion to try pressure bleeding. I made my own pressure bleeder and did not bleed the MC ahead of time. I had the entire car done in 30 minutes. Rock hard pedal. I will never bleed brakes any other way.
PMD24
04-09-2025, 08:24 PM
Or pressure bleed in 15 minutes, and done.
212160
Second that!